Testing device for telephone exchange systems



Oct. 11, 1932.

G. C. HARTLEY TESTING DEVICE FOR TELEPHONE EXCHANGE SYSTEMS Filed July 8, 1931 4 Sheets-Sheet l INVENTOR By acHARTLm I 6P6. M

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A TTORNEY 1 Oct. 11, 1932.

G. c. HARTLEY TESTING DEVICE FOR TELEPHONE EXCHANGE SYSTEMS Filed July 8, 1931 4 Sheets-Sheet 2 QWN k Mnww mm u E Rm u n v R IN l/ENTOR ac. HARTLEY A TTORNEV Get. .119 196312. G. c. HARTLEY 1,881,544

TESTING DEVICE FOR TELEPHONE EXCHANGE SYSTEMS Filed Jul 8, 1951 4 Sheets-Sheet 5 E INI/ENTOR g i 6. c. HARTLEY A TTORNEV Oct. 11, 1932. s. c. HARTLEY TESTING DEVICE FOR TELEPHONE EXCHANGE SYSTEMS Filed July 8, 1931 4 Sheets-Sheet 4 IN VEN TOR 6.6.HAR7'LE) BV ATTORNEY Patented Oct. 11, 1932' same STATES PATENT oF' FicEt Gunner: .cmrronn HARTLEY, or ALDWYCH, Lennon, ENGLAND, assrenon mo wnsrnannnncrnzc cor-arena, INCORPORATED, or new YORK, 1v. Y., A conronaanon on nnwyonx TESTING .DEVICE FOR TELEPHONE EXCHANGE SYSTEMS Application filedJuly s, 1931, Serial Man ma inGreat Britain October 23, 1930.

This invention relates to a routine test circuit for testing subscribers line circuits, trunks, or tie lines either'in automatic, semiautomatic or manualsystems. In'theopera- 5 rtion of a telephone exchange system'it is important to maintain a high standard of 0perating efliciencyin the circuit paths over which subscribers have access to responsive means 7 in the exchange, since unstandard conditions ['10 :on subscribers lines would ordinarily cause the isolation of such subscribers. It is therefore'the object of this invention to provide automatic means for making tests of subscribers line circuits periodically whereby any :un'standard condition may be detected all times in efficient working condition.

In accordance withthe present invention,

the testing device' comprises a distributing switch for successively selecting final selectors whlch have access to the lines to, be tested, a sequence switch for successively applying the required tests to each line selected for testing, and a line indicating switch which is advanced each time a new I line fis seized for test and which causes through banks of lamps the number of the particular line under test to be displayed.

1 The'lsequenceswitch is arranged .to advance step by step to successively apply the pre scribed tests to the particular line under test unless a test failure or unstandard condition 1 for a particular testis encountered in which event an alarm isoperated to indicate a test failure. l lol'lowingrthe successful test of a line the test circuit causes the final selector 1 which is at the time associated with thetesting deviceto be advanced to the next line in its bank. Whenall lines accessible froma particular finalselector have been tested, the f distributing switchis advanced to; select anotherfinalselector and tests-are then made on. all'line'sto whichsuch final selector has aceess' The advance of the sequence switch for and remedied to thus maintain such line at tion, eighteen test positions being provided as follows:

1. Test for busy condition of the line to be tested. I V

2. Test for dead number. 3. Test of line relay feed. 7 4. Test of idle condition on sleeve conductor of line.

5. Test to determine if the line relay'is disconnected.

, 6 and 7. Line insulation line conductor to ground.

8 and 9. Line insulation test for negative test of negative line. conductor to positive line conductor.

"10a Discharge of potential from substation ringer condenser so as not to interfere with theqnext test.

11 and 12. Line insulation test of positive line conductor to ground.

13. Discharge of potential from substation ringer condenser so as not to interfere with the next test.

14. Test to deternnne if the ringer condenser has been discharged.

15.-Co1npletion of ringer condenser discharge.

16.. Release of cut-off relay.

17. Line finder of first bye-path operated to find line and is released. V

18. Sequence switch is returned to normal 7 and the final selector is advanced in synchronism with the line number indicating switch.

To provide for the automaic advance of the sequence switch in positions 8 to 12 inclusive for makingline insulation tests, a thermionic valve relay is provided which operates to open the magnet circut of the sequence switch only if the line insulation is found to be in unstandard condition.

For a-clearer understanding of theinvention reference'may be had to the accompanying drawing taken. in connection with the v V Fig. 4 showing a bye-path switch which is common to a plurality of final selectors, such as-the final selector of Fig. 3 Fig. 5 is a diagram showing the manner in which the severalsheets of drawings should be arranged to show the completeinvention.

The testing device functions in the follow ing manner, it being assumed that the digits 1,1 are first sent to the final selector stage for the purpose of nitiating tests Seizure of line for testing When the test man operates the: start key 201 a circuit is established from ground over the back contacts of relay 202, right back contact of relay 203 to battery through the winding of relay 204,- but relay 204 being slow to operate, a circuit isestablished for relay 205 before relay 204-operates which may be traced from battery, windingof relay 205, back contact of relay'204, thence as traced to ground at key 201. Relay 205 upon Operating closes a circuit for relay 206, extending from battery, winding of relay'206, right-icontact of relay 205, back contact of relay 202 to ground at key 201, relay 206 looking over its inner contact to ground at key 201. As soon as relay204 operates the operating circuit of relay 205 is openedbut a holding circuit therefor is closed overits left frontjcontact and the outer contact of relay 206 to test wiper 207 of'the distributing switch 200 and; to ground at the'final bye-pathswitch if it is busy.

f the final bye-path i5 free,'relay 205 releases and a circuit is established from ground throughtheleft winding of relay208, left back contact of relay 205, outer contact of relay 206,.wiper 207 and associated bank terminal. conductor 209, inner left back contact of relay 301, outer left back contact'of relay 302, conductor 303, inner left-back contact of relay 400,.conductor 401, normal terminal andwiper 304 of switch 330, next to outer right back contact of relay 402, middle I left back contact of relay 403, wiper 305 and associated normal terminal, inner right back contact of relay 400,;resistance'404 to batte'ry. vRelay 208operates in this circuit and locks from battery through; its right winding and inner right contact, right back contact of frelayri203, back contact ofv relay 202 to a. ground at'the key 201, and at its next to inner rightcontact connects direct ground to thewiper 207 to renderthe bye-path busy to other calls. Relay'208 also closes a circuit from ground through'the right Winding of relay 203, outer back contact of relay 210, inner left contactof relay 208, wiper 211, con

ductor 212 to battery through the impulsing relay 405 of the bye-path. Relay 203 does not operate in this circuit as the resistance of relay 405 is too great but relay 405 operates and'closes an obviouscircuit for relay 400 which operates and locks over its inner left front contact, conductor 303, thence as traced over wiper 207, to ground'at the next to-l inner right front contact ofrelay'208-;cir-

cuit is now closed for relay 410 extending from battery, right winding of relay 410,

inner right back contact of relayi406 to ground at a front contact of relay 400. I

At its" outer 'left front contact relay 208 connects interrupted ground through the winding of relay 213 which upon each 6116 13:

gization closes an obvious circuit for slowreleasing relay 210. Relay 213 at its :outer contact also shunts the outer contact of relay 210 so that when relay 210 operates to open itsback contact the circu t previously traced for pulsing relay 405 is maintained. When rel'ay213 now releases and before :relay 210 has time to release the circuit of relay; 405- is opened and transmits an impulse through the windingof stepping magnet-3060f switch 330, inner left back contact of relay 406,11ext to inner right front contact of relay 400, Wind- 7 ing of; slow-releasing relay 7 407, back contact "of relay 405 to ground at theinner left back contact ofirelay403. -As soon relay 210 releases, relay 405 again energizes opening the circuit' of magnet- 306. Switch 330 is;

therebyfadyanced one step closing a circuit extending from battery through the winding.

and interrupter contacts" of magnet 307, wiper 308 and normal terminal of switch 350, outer left-front contact oflrelay 400, wiper 309. off-normal segment 310,',outer le'ft back-contact of relay 406, back contact of re lay 408 to ground ,attheright back contact or} relay 403,, However, before magnet 307 canenergizea circuit is established for relay 408 extending from battery; through its wind ing, wiper311and No.1 terminal ofthe co'- operating 7 bank of; switch 330 strapped to the normal terminal with whichwiper 305 of" switch 350 is in engagement, inner right front contact of relay 400,,outer right backcontact of relay 406 toground at the outer rlght front contact of relay 400. Relay-408 upon operating opens the previously Qtraced' circuit forv magnet 307,

Upon the termination ofthe impulse relay 405 reoperated, it opened the circuit of slow-to-rele ase relay 407 whichafter an interval releases, "closing a circuit for operating relay 406 extending frombattery, winding of relay 406, right back contact :of relay 407,

right fronticontact of relay408 to ground-at the right back contact of relay 403; i-Relay 406-then looks over itsginnerright front contactto groundat the next-to outer right con-' tact'ofrelay 400 and closes aholding circuit for relay, 410 extending frorn battery, right winding and outer right front contact of relay 410,'next to outer right frontcontact of relay 406 tosground at'the left contact of relay 407.

- VV hen relays210 'and213 operate to transmit a second impulse relay 405 again deenergizes and since relay 406 is now operated. a circuit isestablished from battery through the wind-v ing-of magnet 307, left back contact of relay 409, inner left front contact of relay 406, next to inner right front contact of relay 400, winding of relay 407, back contact of relay 405, to ground at the inner left back contact ofrelay 403. Magnet 307 and relay 407 operate, relay 407 opening-the holding circuit of relay 410 which now releases, Magnet 307 advancesthe wipers of switch 350 one step thereby releasing relay 408 which closes a circuit for magnet 306 extending from battery, winding andinterrupter contacts of magnet 306, outer left front contact of relay 406, back contact of relay 408 to ground at the right back contact of relay 403. 'Magnet 306 now advances its wipers step by step to hunt for an idle final selector, When an idle fin al selector is foundsuchfas the selector of r 3, a circuitisestablished from battery,

winding of relay408, wiper 311, inner left 7 back contact ofrelay 302, outer left back contact of relay 301,0onductor 214, wiper 215 to ground at a front contact of relay 208. All. busy final selectors will. have their test circuits F corresponding to the circuit just traced open at contacts of their relays cor- 40 responding to relay-302.

Relay408 upon operating opens the 'stepping circuit of magnet 306 and completes a circuit for magnet 320 of the selectedqfinal selector 300 from battery. winding of magnet I of relay 411, left contactof relay 408, outer 320, wiper 312 ofswitch 330. left back contact right back contact of relay 402, right back contact of relay 412, wiper 313, to ground at the'interrupter contacts of magnet e320. Under the control of magnet 320 the final selector hunts for theline marked byethe switch-350. When this line is found relay 411 operates in a circuit extending from b attery, left winding of relay 411, inner right back contact ofrelay 414, wiper 331 of switch 350, marked terminal upon vwhichwiper 331' has-been positioned strapped to the marking multiple of switch 300 to which wiper 314 has gfaccess, wiper 314', terminal of switch 330 to groundon'wiper -315, Relay411 operates f openingthe previously traced circuit of mag- V the terminal of the rnarked line in itsbank,

net 320 to arrest the'wipers of switch 300 on lt will' be noted that relay 411' will operate from battery through the winding of relay 403, outerright front contact of relay 409, right backcontact of relay 415, inner left frontcontact of relay 411, left front contact of relay 408, outer right backcontact of relay 402, right back contact of relay 412, wiper 3'13 ofswitch 330 to ground at the interrupter contacts of magnet 320. Relay 403 upon op erating locks over its inner right front cont act to ground at a front contact of relay 400.

Upon theoperationof relay 403 a circuit is established from battery, winding of re lay402, outer left front contact of relay 403, conductor 416, wiper 216 to ground at the outer right front contact of relay 208 thereby operating relay 402 which opens the c'ircuitof relay 409. Relay 402 also establishes a circuit for relay 302 of the final selector extending from battery, winding of relay 302, rightback contact of relay 301,

wiper 315 of switch 330 to ground at the,

out-er left front contact of relay 402. lVith relay 409 released and relay 403 operated battery is connected in parallel with the winding ofrelay 405 to thecircuit extending over 'w iper211 of the distributor switch 200 to the right winding of relay 203, this parallel battery connection extending over'the middle right front contact of relay 403, the

right back contact of relay 409, resistance 417 to battery. Relay'203 now receives sufficient current to operate and locks over its left winding and inner left front contact, back contact of relay 202 to ground at the startkey 201. A circuit is now closed from battery,'winding of relay 301 of the final selector, conductor 217, wiper 218 of the dis-.

tributor switch 200 to ground at the middle 1 I right front contact of relay 203. Relay 301 opens the circuit of relay 302 and connects the sleeve wiper 317 of final selector 300 over the left front contact of relay 301, conductor 214, wiper 215 to ground at a front contact of relay 208. Relay 301 upon operating busies the final selector so that it may not be seized for other connections. Relay 203 upon operating also opens the previously 1 traced circuit for relays 208 and 204 thus re- 1 leasingfrelay 405 in the bye-path. The operation of relay 301 also opens the locking circuit of' relays 400 and 408, relay 400 in turn releasing relays'403 and 406. Relay 403 upon releasing releases relay 402.

7 Upon' tlie release of relay 400a restoringcircuit is established for switch330 'extend ing from battery through thewinding' and interrupter contactsof magnet 306, outerleft back contact of relay 100, wiper 309, off-normal segment 310, outer left back contact of relay 106, right back-contact of relay 408, to ground at the outer right back Contact of relay. 403. Magnet 306 advances switch 330 to normal in which position the.

circuit of relay 111 isopened and relay 4111 releases. A restoring circuit is also estab-" lished forswitch 350 extending from battery through the winding and interrupter contacts of magnet 307, wiper 308 and off-nor mal'segment 319 of switch 350, thence to relay 103; .All apparatus of thebyepath has now been returned to normal. .The testing device havlng nowiselected a subscribers line through thepositioning of final selector 300 is in readiness to. conduct tests on such line. f

When relay 203 operated it closed an obvious circuit for relay 221 and a circuit for operating relay 219 which may be traced fromlbattery, winding of. relay 219', middle left front1contact of relay203, normal ter-.

minal and wiper 102 of sequence switch 100 to ground. Relay 219 locks over the next to innerright back contactof relay 103,.the No. 2contacts of relay21 9, inner right back contact of relay 220 to ground at the front contact of relay 221.- ltelay"219 closes a circuit from battery, left non-inductive winding ofrelayJ104E,.llo. 8 contacts of relay 219,

right operating winding of relay'104 to' ground over wiper 105 and normal terminal 106 of switch 100, Interrupted ground is connected from interrupter 107' over the right back contact of relay 10 1, short circuit ing' the right operating winding or relay 104 Test for z'cllc of busy conditon'of s-ubscflbrs until the interrupter advances toa" position to disconnect this ground. .As soon. as the short. circuit'is removed "from the right winding of relay '10 1,it operates in the circuit previously traced and connects interrupter-107 over, the right front contact of;

relay 104, to battery through the winding of stepping magnet 108 of'switch 100, which advances switch100 one step under'the con-v.

trol ofithe interrupter, V

I line' imcier test If the subscribers line to which connec tion 'hasfbeen made is busyr-elay 1.09 will have operated over a circuit extending from] battery, winding ofrelay 109, normal terminal 110 and: wiper 111, No. 3 contacts of relay 219, wiper 215,'conductor 21 1, left front contactwof relay 301, final selector wiper 317 to ground, on the test" terminal-321: /Vith relay 109 operated, when' s'witch 100, reaches position 1 the initial energizing circuit of are-j 1 lay lO l will" be opened, and. as the locking round as'traced at the right back contact of circilit therefor extending from battery through its left winding over the No. 8 0011- tacts of relay 219, right winding of relay 104, wiper 105and No. 1 terminal with which it is in engagement'to ground at the back contact of relay109 is opened, relay 10 1 re-- leases, holding switch ineposition 1. A

circuit is now established for relay 116" ex tending from battery,fwinding ofrelay 116, No. 1. terminal-with which wiper 119 is now in engagement toground at the No. 7 contacts or relayi2l9. :Relay 1'16in turn closes an obvious circuit for relay 118. Switch 100 ,will remain in this position until the subscribers line becomes free and relay 109 re-* leases; When relay 109freleases, relay 104 operates over the circuit just traced and again connects interrupter 107*tothe winding switch 100' into position 2.

1 to determine if the seZectcd Zinci tcrmiI- w nalsare dead In positions "1 and 2 the circuit of relay 112 is closed over wiper 113 to short circuit retard coils 114-. and 115 whichare normally connected into the positive. and negative leads of the testing device. With switch 100 in position 2a holding circuitis established from battery, winding of relay 11 6,Iw1per117,;

no. 'tcontacts of relay 2-l9,innerrightj front contact of relay 112,rwiperf221, conductorr ing of steppingmagnet 108 thereby advanc- 222,*wiper-322 of the final selector to line terminal 323'. lfrelay llfifreleases indicating that there, isno groundhon the terminalon.

which wiper'322 .is resting, and therefore that the line terminal, to which the final selector has been advanced may jbe' dead or 7' blank affurthertest is madefto insure-that the former test has been accuratelydnade,

through the connection of relay'l18ovei? the inner left bac-kcontact of relay 116,-0uter right contact of relay 118, No. 2 terminal with which wiper 120 now engages, No. 5

contacts of relay 2l9, outer contacts ofrelay.

112, wiper 223, conductor 224i, wiper 3245 of the final selector, terminal 325, right-back contacts of relay 118 to battery" through the winding of an 1215.; Relay'121' Will then oper'ateand at its-innerifront contact" will extendits operating ground to; operate relay 103. Relay; 103 then opens the circuit of" relay 219. .Nith'relay 219 released a restoring circuit isclosed for switch 100extending from battery, winding 30f magnet 108, No, (ibackcontactof relay 227, interruptoer contacts of magnet; 108, outer-fightback {the operating circuit of magnet 108 when Wiper 102 leaves thesegment 122, relay 103 1 remains locked over its outerTfront coutact to ground over oif-normal segment 122 and wlper 102.

When relay 103 operateditalso closed a the circuit from ground at middle right front, contact of relay 203, m1d'dle fightback I contact of relay 228, No. back contact of. relay 227, next-to outer right front contact, of relay 203, wiper 229, conductor 230, Winding of stopping magnet 320 of the final selector to battery. When, therefore, relay 103 releases as soon as switch 100 reaches normahthe circuit of magnet 320 is'opened and the final selector advances to the next line terminal in its bank. Testing.willthen start as previously described on the newline. 1 1 If the line first selected, however, is a normal "line connected for service then with switch 100 in position 2 relay 116 would have operated and relay 118 wonld have re:- leased thereby establishing the 'c1rcu1t of relay 104 irom battery, left winding of re lay 104, No. S contacts of relay 219, rlght l0v winding of relay 104, wiper 105 and No. 2

' terminal to ground atthe leftfront contact of relay- 116. ills-previously described relay 104 upon operating causes the advance 1 ofv switch 100 into position 3. 1 5 I V I v i Test of-Z-ine relay feed I With switch 100in position 3 relay 123 is connected in .aloop circuit extending from battery, winding of the subscribers line relay 326', right back contact of' cut-oil relay 318, terminal 325, wiper'324, conductor 224, wiper retard coil'115v, No. 5contacts of relay 219, wiper 120 and the No. 3 terminal of its bank, winding of relay 123, outer left back contact ofrelay 109, which released when switch 100 left position 2,. No. 3 term nal and wiper 117, No. 4 contacts of relay 219, retardcoil 114, wiper, 221., conductor 222,

Wiper 322, terminal 323 to ground at the in her back contact of cut olf relay 318. Relay 124 is also connected from ground over a portion of the circuit traced to ground at the back contact of-cut-oflrelay 318. Relay 123 should operate at this time if the subscribersline is ,inithe proper condition to feed current to the winding of the line relay but relay 124 should not operate. Under this conditiona 6O circuit is'estahlished for relay 104 as previously traced to wiper 105, thence over the third position terminal with which it is en'- gaged, back contact of relay 124 to ground at thefront Contact of relay 123. Relay 104 thenadvances switch 100 into position 4;

. Test of free condition of sleeve wire of the subsoribers Zine With switch 100 in position 4, a circuit is established for relay 125 extending from ground, right winding of relay 125, terminal wiper 111, No.3;contacts of relay 219, wiper 215, conductor 214, left front contact of relay 301, wiper 317, terminal 321, back contact of relay 326, outer left back contact of relay 318 to battery through the left Winding of relay 318. Relay 125 should operate this time and in operating closes a hold- :circuit for itself over its left winding and left right back contact of relay 103, elf-normal segment 122 to ground on wiper 102, and a circuit for relay 104 extending as previously traced from the wind: ings of relay 104 to wiper 105, thence over the No. 4 terminal with which this wiper is in engagement to ground at the right contact of relay. 125. Relay104 upon operating advances switch'100 into position 5 in the manner previously described. In positions 5 to 15 inclusive direct ground is connected over wiperlll and the circui traced to cut-off relay 318. Relay ,318 operates opening its outer left back contact to disconnect its left winding from sleeve terminal 321, thereby increasing the potential on terminal 321 to renderthe subscribers line unselecta-ble to other final selectors and opens the circuit of line relay 326 to prevent the subscriber from initiating a call.

Z 6825 to determine Zine relay is disconnected With switch 100 in position 5 a circuit is established from ground, winding of relay 124, outer left back contact of relay 109, winding of relay 123, No. 5 terminal with which wiper 120 is in engagement, wiper 120, llo. 5 contacts of relay 219, retard coil 115, wiper 223, conductor 224, wiper 324 to terminal if the cut oif relay 318 has operated as it should have to disconnect the winding of line relay 326, this circuit will not be compl ted over the right back contact of relay 318 to battery through the winding of relay 326' and ther fore relays 123 and 124 willnot operate and a circuit will be established for relay 104 extending as previously traced. through the windings of this relay to wiper 105, then over the No. 5 terminal of its bank to ground at the back contact of relay 123. Relay 104 thereuponoperatesto cause the advance of switch 100 into position 6. Testing of the line insulation of the subscribers'line now commences.

The grid 'ofavalve127 ,is now. connected in parallel with resistance 128 and battery 129 over the No; 6 terminal and wiper 120 of switch. 100,110. contacts of "relay 219, re

2;"; tard coil 115, Wiper 2 23,1conductor 224, wiper 324, terminal 325 to the-negative or tip conductor of the line under test. ,The cathode of the valve is heated over a circuit includthe cathode battery 130, rheostats 131 and 132-and key 133, the potential on the cathode being Controlled. by the rheostats.- If now the, leakage resistance from the negative line conductor, to ground is less than a certain value the grid will be made sufficiently positive with respect to the cathode to allow enough current in the plate circuit to operate a plate relay 134. Theactual value of line leakage at which relay 134 operates canbe varied by varying the'value of resistance 128 which is'of the order of 90,000 ohms or b'y changing the potential of the cathode or both. If,

upon the test of the insulation resistance of the negative conductor, relay 1 34 does not operate relay'104 is operated over the circuit previously traced through its windings to wiper 105, thence over the No. 6 terminal with which this wiper is in engagement to ground at the back Contact of relay 134,

i Switch 100 is then advanced in themanner previously described into position 7 w h ere the same testis continued. If the condition of the negative, conductor is still found to be standard switch then advancesfinto pov sition 8 in the same manner.

Zine insulation test between positz'we and negative Zinescondnctors With switch l OOin position 8 the'grid of the thermionic valve is again connected to the negative or tip conductor of the line under test and a direct ground is connected to the positive or ring line conductor extending from the No. 8 terminal with whichwiper 117 is in engagement, wiper 117, No. 4 contacts of relay 219, retard coil 114, wiper 221, conductor222, wiper 322, terminal 323 to the positive line conductor. If relay 134 now fails to operate indicating that the insulation between the hne conductors is correct relay 104 operatesover the previously traced circuit advancing switch 100 into position 9 where this test is again repeated and switch 100 is advanced into position 10.

Line insulation test of positive conductor to ground a control. of relay. 104 into, position 11. in? the same manner in whichit :was advancedijinto position10. With switch 100- in positionll ground is connectedfover wiper 120, to the negative conductor of the subscribers line over the circuit previously tracedand the grid ofthe valve 127 is connected over wiper 117 and the circuit previously traced to the positive conductor ofthe line. If there isno unstandard leakage to ground from the positive conductor, relay 134 will not operate and the 'previously'traced circuit for, relay 104 will be established atthezback contact of relay 134 whereby relay'104 will operate to advance switch 100 into position 12. In position 12 this test is continued and switch 100 is ad'- vanced'into position 13. The'connection of ground to the negative line in this case does not mean that the line conductor to line conductor-insulation is beingtested'as this condition was tested previously. In position battery through low resistance 135 is connected to the positive line and direct ground to the negative line in the same manner as in position 10 to charge the ringerconden-ser 327 in readiness for the next test. Direct ground on the No. 13termin a1 over wiper which isresting thereon, operates relay 104 ,tofadvance switch 100 into position 14. I

Substation ringerdz'scharge test With switchlOOinf position 14 the grid of valve'127'and battery 129 through resistance 128 are connected over fwiper 120 to the negative conductor of the subscribers line and the positive conductor of the line is grounded over wiper 117. Thus, the subscribers ringer condenser 327 which was fully charged in position 13 is now discharged through resistance 128; The current from the condenser discharge causes a change in the grid potential of valve 127 and the corresponding surge of space current through thewinding of relay 134.;1Relay 134 should operate at this time and close a circuit from; ground on its front contact over the No. 14 terminal and engaged wiper 136,'to battery through the winding of relay 137. Belay'137 upon operating looks over its left'contact, outerright back contact of relay 1,03, oii normal segment 122 to groundon'wiper 102. -At'its inner right contact relay 137' closes a circuit from battery as traced through the windings of relay104 over wiper 105 and the No. 14 terminal of its bank, to ground at the inner right contactof relay 137. Relay104 in the manner previously described advances switch 100 into position 15. The retard coils 114 and 115, already referred to, connect the positive I and'negative conductors at the testing device to the testing device and serve to prevent the discharge ofthe ringer condenser 327 from being sufficiently violent to tinkle the ringer and also prolong the discharge thereof, therebygiving relay 134 sufiicient time to operate.

In position 15 the dischargeofthe ringer condenser 327 is continued but-in this position batterythrough a lower resistance 135 is con-- "nected to the negativeline conductor in place of: battery through the high resistance 128 line under test 'With switch 100 in'position 17 a loop is closed from battery, windingof the subscribers'line relay 326, right back contact of relay 318, 1terminal 325,*wiper 32 1, conductor 222, wiper 221, retard coil 111, No. 4 contacts of relay 219,. wiper 117, N0; 17 terminal with whichwiper 1:17 is in'engagement, inner left backi contact of relay V 109, high resistance 138, No; 17 terminal with which wiper is inengagement, thence as traced to terminal 323 and grou'nd'at the inner left backcon tact of cut-o'fi relay 318.= Relay. 326 operates in thiscircuit land at its right contact closes the usual: line'finder start circuit 328. As

'seon as'the line findennot shown, has seized the subscribers line over multiple terminals 329, the cut-off relay 318'operates over the line finder sleev'eterminal, left'front contact 'ofTre1ay'326 and righ t winding of relay 318, relay 318'now being held operated over its right winding, outer left front contact to ground on the line finder sleeve terminal. Relay 318 also disconnects ground from the positive line conductor and the winding of line relay 326 from the negative line conductor whereupon relay 326 deenergizes. I

Acircuit isnow established from ground on the line finder sleeve terminal, outer left front-contact of relay318, left'back contact of liner-clay 326, terminal 321-, wiper 317, left front Contact of relay 301, conductor 214, wiperi215,No. 3 contacts of relay 219, wiper 111 i-n engagement with the No. 17 terminal ofits bank, to battery through' the winding of relay 109. Relay 109 operates, discon- 'n'ect-ingresistance 138 from the loop previously traced and connecting the lower resistance winding of relay 123 therein. 'Relay 123 now should operate from battery in the first bye-path associated with the line finder but its resistance 18 such that the byep'ath'is not operated ofi normal and no unnecessary wear is introduced into the first bye-path. If relay 123 operates indicating that the subscribers line circuit will function correctly to initiate a call, a'circuitis closed from ground at its front contact, outer right front contact of relay 137 to battery through the winding of relay 1395' Relay 139 oper ment 232,

ates and closes a circuit forrelay 104 extending as previously traced through the wind ings of relay 10 1 to wiper 105. No. 17 terminal with which wiper 105 is in engagement, front contact of relay 139, outer right back contact of relay 103, elf-normal segment 122 to ground at wiper 102. in the manner previously described switch 100 is advanced into position 18 in which position relays 123 and 139 release. 7

With switch 100 in position 18 a circuit is established for relay 103 extending through its winding, the No. 18 terminal with which wiper 119 is now in engagement to ground at the No. 7 contacts of relay 219. Relay 103 upon operating locks over its outer right front contact to ground over the olf-normal segment 122 and wiper 102 and opens the circuit of relay 219. Relay 219 upon releasing advances switch 100 into its normal position 111 the manner previously described. With switch 100 in its normal position relay 103 releases. As previously described the final selector is advanced one step to select the next subscribers line terminating in its bank for testing.

Line number indication relay 221 operated after the line was selected a-oircuit was established for the tens indicating lamp 231 from battery, lamp 231, sjeg wiper 233 to ground at the front contact of relay 221, and a circuit was established for units indicating lamp 234 over terminal. 235, wiper 236 to ground at the front contact of relay 231. Lamps 231 and 23 1 being lighted indicate the tens digit one and units digit one of the line'under test. The thousands and hundreds digits are indicated by the position of switch 200 which selectsthe particular final selector having access to the line under test. I

WVhen relay 103 operated upon completion ofthe test on the line it closed a circuit for magnet 237 extending from battery, winding of magnet 237 left back contact of relay 223," left back contact of relay 227 to ground at the inner right front contact of relay 103 and as soon as relay 103 released upon't-he return of sequence switch 100 to normal, magnet 237 released to advance the wipers of switch 250 one step. in its advanced position circuits are now established for tens lamp 231 and units lamp 233 to indicate that line No. 12 is ready to be tested. It will be noted therefore that since relay 103 is instrumental in advancing been the final selector and the number indicating switch 250 that these switches advance in synchr-onism. When switch 250 has advanced to thelast its terminal set ofitsbanh or when the test of L 20 7 switch 200 one step. With switch 200 adfinal selector 300 has been completeda circuit is established for relay202, extending through the winding of relay1202,,terminal 239, wiper 236 to ground at'the front contact of relay 221. Relay 202 upon operating releases relay 203 in turn releasing relay 221.

Relay 202 closes a; circuit from battery, windingof stepping magnet-240 of distribe utingswitch 200, front contact of relay 202 to ground at start key 201preparatory to advancing switch 200. Relay 221 upon deenergizing closes a circuit for magnet 237 extending from battery, winding and interrupter contactsv of magnet 237, ofi-normal segment 241 and wiper'242 of switch 250't0 ground'at the back contact of relay 221 whereupon magnet 237 advances switch 250 intonormal position,opening its own circuit and also opening the circuit of relay 202 which in turn releases magnet 240 to advance vanced a new final bye-path is seized and the testing device'then functions to select an idle final selector associated with the selected byes path and to conduct tests on, the one hundred lines to which this final selector has access.

Faueltalarr'm V When relay 219'operates at the'beginning of thetest of a line under test a circuit is closed from ground at interrupter 243, No. 9 contacts of relay 21 9, leftwinding of relay 244jto battery, thereby operating relay 2 44 as soon as the'interrupt'er closes its back con v left, front contact of relay 219, inner right tact. Relay 244 locks over its inner right contact, left back contact of relay 104, inner back contact of relay 220 to ground at the I front contact of relay 221 and closesa circuit contact and the left contact of relay 244,

closing the circuit of fault lamp 246 and giving the switch 100 three minutes to advance following any particular test.

'During anyone of the tests made in any I position of switch100 slow releasing relay ground at the front contact of relay 221 and 210operates over the left front contact of relay 104, inner left front contact of relay 219, inner right back contact of relay 220, to

if during testing this relay releases a circuit is closed from ground over wiper 102, seg-. ment 122, No. 6 front contact of relay 219, inner back contact of relay'210, outer right back contact ofrelay'121 to battery through the left winding of alarm relay 228. Thus,

if switch 100 is'stopped for more than the releasing time of relay 210 or 300 milliseconds,

alarmrelay 228 will atonce operate. This latter period would betoo rapid for the tests made ineposition 1 and position 17 of switch 100, which tests are for the busy-conditionof the selected subscribers line and the selection of the lineby a first bye-path line finder. Therefore, in position 1 a direct circuit is established for relay210 over the right front contact of relay 109 and in position 17over wiper 113 to ground. I V- When alarm relay 228 operates a circuit is established for relay 103 extending through its winding, No. 3 back contact of relay 227, to groundat theinner rightfront' contact of relay 228,. and relay 103 in the mannerpreviously described causes switch 100 to be advanced to normal thus releasing relay 219 in turn releasing relays 244 and 228. While relay 228 is releasing, it being slow to release,

a circuit is established for relay 227 extending, from battery, winding of relay 227,

'middle back contact of, relay 121, inner left front contact'of relay. 103, outer left front contact of relay 228 to ground. Relay 227 operates and locks over the middle back contact of relay 121, outer left front contact of relay 227, normal contact'of key 245 to groundat the start key 201., With either relay 228nor 227 operated'neither the" number indicatingswitch' 250 nor' final selector can be advanced and therefore when sequence switch 100 reachesnormal testing-will restart on the same subscribers line- J If the faultreoccurs relay 228 will operate again but with relay 227 operated relay 228 cannot reoperat'e relay 103 since its circuit is opened at'the inner right contacts of relay 227 but relay228 willclosethecircuit of relay 220 from battery, Winding of relay 220, No. 7 contacts of relay 227, No. 1 contacts of relay 219 to ground atthe outer left'front contact of relay 228. Relay 220 looks over its left contact, normal contact'svof key 245 and contacts ofstart key 201 to ground. Relay 220 at itsouter right front contact may close the circuit of a fault lamp 246 or other signal device that may be required. This facility for dropping ofl'cthe lineon the first fault indication and retesting' iszrequired to cater for the case of the subscriber instituting a call during the 'coursefof the test. In this case when the second test commences the line will be found busy and thevtest will be suspended until the subscriber has finished unless the conversation is unusually long when a fault is recorded. 'When relay 227 operated, the release of relay 219 does not cause switch 100 to return to normal under self-interruption but causes it to'stepin a circuitextending from battery, winding of magnet 108, No. 6 front contacts of" relay 227, outer left front contacts of relay 103 to ground at interrupter 107. This introduces a sufficient delay before recommencing the test to make quite certain that the subscribers line has'been picked up .by thebyepath finderand accordingly tests busy. i

If the second series of tests is made with out a fault indication thenlwhen switch 100 reaches position'18 a shunt is. connected about the winding of relay 227 over the 'No. 18 terminal upon which wiper 119-is resting to ground at-the No. 7 contacts of relay 219 and relay 227 .releases so that the normal number oftests will be'made on the'next 'line selected for testing. When either relay 227 or 220 is operated and locks it may be released by depressinglkey 245. A Switch 200 may, if desired, be advanced to selectany ingdevice to select a desired one of said lines,

testing means in said testing device-to deterininethe busy or idle condition of sa1d line,

-means operative by said testing means it said line isfound to be idle to progressively applya series oftests to said line, and 'means operated by said testingmeansnf sa1d line is 'found to be busy to cause said testing device to wait; until said 'line becomes idle be- 7 fore-per1nitting theapplicati on of said'tests.

- a selector switchassociated withsaid 2. In 'a telephone exchange system, a plurality of subscribers lines, atestingdevice, a selector switch associatedwith saidtesting'device to select a desired one of said lines,

testing means in said'testing device .to de 4 termine the busy or' idle condition of said line,.means operative by said testing means only'it said line is found tojbe idle to progressively applya series oftests to said line, analarm signal, and timing means for operating said alarm signal after a predeterminedinterval if said line is foundto be p 3. In a telephone exchange system, a plurality of subscribers lines,a testing device,

a selector switch associated with said test ing device to select a desired one of said lines,

testing means in said testing device to 'determine the busy or idle condition of saidline, means operated by saidtesting means only if said line is found tobe idle toiprofgres sively apply a seriesxof tests to said line n alarm signal and timing means for operating said alarm signal. after a suflicient interval to permit the call on said line tobecome terminated if said line is found .to be usy- 4. In a telephonee rchange system, a splurality of 'subscribers lines, a testing device,

progression switch "in said testing device for f lamps "for indicating selected.

, detected I ing' device a "progression switch in said testing device ti device to select a desired one of said'lines, a

successivelyapplying a series of tests to said line, means operative if the terminalvof said selected line is idle for advancing said progression switch and means operative ifsaid line terminal is found to :be blank or not 'connectcd'to'a line in service to immediately instoreisaid progression switchto normal.

5. In a telephone exchange system, a plurality ofsubscribers lines, a testing device, va selector switch associated with said testingdevice to select a desired one of said lines,

progression switch in said testingdevice for successivel a 1 in a series of tests to said line, means operative if the terminal of said selected line 1s idle for advancing sa1d progression switch, means operative it said ,line terminal is found to be blankor not connected'to a line in serviceto-immediately restore saidprogression switch to normal, and :means zforthereupon advancing said selector switch toselect another subscribers line.

6. .In, a telephone exchange system, aplu- ;rality; of subscribers lines, a testing device, a

selector switch associated with said testing device to select lines in succession, means to progressively apply a series of tests to each .line selected, means operative uponthe completion of the prescribed-tests of a subscribersline to advance said selector switch to select another line, a line number indicator and means for operating said "line number indicator in synchronism with said switch to indicate the number of each line selected.

7. In a telephone exchange system aphirality'of subscribers lines, I a selector switch associated with'said testing device to select lines in successiommeans to progressively apply a seriesof tests to each line selected, means operative uponlthe completion of the prescribed tests of a sub scribers line to advance said selector switch to select another line,'a line numberindicator comprising a register switchan d banks of indicating lamps, and means for operating said register switch in synchronism, vith said selector switch to selectively light said the number of each' line rality of subscribers" lines, o a testing device,

a selector switch associated with said/testto selecta desired onefof said lines,

for successively applying a series oi tests to sa1d lme,means operative if nofaultfis'detected on any of said tests forresto'ring said a testing device,

ing, meansoperatlvelf a fault 1s detected to "progression switch and for advancing said selector switch to select another line for testmeans for thereupon advancing said progression switch 7 line."

to repeat said tests on the same 10. In a telephone exchangesystem, a plurality of subscribers lines, a testing device, a ,selectorvswitch associated with said testing device'to select a desired one of said lines, a progression switch in said testing device "for successively applying a series of tests to said line, means operative if'no fault is detected on any'of said tests for restoring said progression switch and for advancing said selector switch to selectanother line for testing, analarmsignal, means operative if a fault is detected to restore said progression switch without advancing said selector switch and to operate said alarm signal, and automatic means for thereupon advancing said Iprogression switch to repeat saidtests onthe same selected line. I 11. Ina telephone exchange system, a plurality of subscribers lines, a testing device, ,aselector switch associated with said testing device to select a desired oneof said lines, a progression switchin said testing device for successively applying a series'of tests to said line means 0 erative if no fault is detected on any of said tests forrestoringsaid progression switch and for advancing said selector switch to select another'line fortestfrestore said progression switch without advancing said selector switch, automatic means for" thereupon advancing said progression switch to repeat said tests on the same selected line, and means operative if no fault is detected on the second teststo again restore said progression switch and to advance said selector switch to select another line for test- I 12. Ina telephone exchange system, a subscribers line having a plurality of conductors, a testing device, means for associating said testlng devlce with the conductors of jsaid line, a progression switch in said testing devlce for successlvely applylng nsulav tion tests to the conductors of said line, and

means for automatically advancing sai'd'progression switch it the insulation of said con ductors is found to be in normalor standard condition.

'13. In atelephoneexchange system, asubscribers line having a plurality of conduc- 5 tors, a testing device, meansfor associating said-testing device' with the conductors of said line, a progression switch in said testing" device for successively applying insulation' tests to the conductors of said line,a'

thermionic valve for detecting I an unstandard condltlonof lnsulat'ion resistance on sa1d conductors, and means controlled %by said valvefor arresting the advance of said pro 'gressionswitch it an unstandard' condition of insulation resistance isfdetected.v C c 14. In a telephone exchange system, a sub scribers line having a plurality of conducstandard condition of insulation resistance is detected. y u 1 15. In a telephone exchange sy stem,-a subscribers line having a plurality of conductors, a testing device, means for associating said testing device with the conductors of said line, a progressionswitch in said testing' device for successively applying insula- ,tion'tests from each oflsaid conductorsto ground and between said 'conductors,a thermionic valve for detecting an unstandard condition of insulation resistance, a" relay controlled by said valve for arresting the advance of said progressionswitch if an unstandard condition of insulation resistance 7 is detected, andmeans controlled by said switch for discharging said line conductors betweensuccessive tests. 1 V o c 16; In a telephone exchange system a subscribers line having a plurality of conduc- ,lOO

tors, a testing device, a thermionic valve in I saidtesting device, means for connecting one of said lineconductorsto ground and the other of, said line conductors to battery through resistance and to the grid of said valve,'a potentiometer comprising in part the line leakage, resistance fromsaid other line conductor to ground for controlling the potential on said grid, potentiometers for varying the potential on the cathode of said valve and means responsive to said valve iftheline leakage resistance ofsaid other conductor to ground is less than. a 'predetermined value.

17. In a telephone exchange system, a sub scribers line having a plurality'of conductors, a testlngdevlce, a thermlomc valve 1n saidtestlng device, a progression switch for successively connecting said line conductors to battery through.resistance and to the grid of said valve, a potentio'meter comprising in part the line leakage resistance'from 'theline conductor connected to said grid from ground, potentiometers for varying the potential on the cathode of said valve, and

means responsive to said. valve if the line leakage resistance of'the conductor under test .to ground is less than a predetermined value for arresting the advance of" said switch,

7 p 18. a telephone exchange system, a subscribers line having responsive apparatus and a plurality of line conductors, a testing device, means for associating said testing device with said line conductors and responsive apparatus, a progression switch, means con- 

